This invention relates to a mounting device and, more specifically, to a device for mounting a truck body to a truck frame.
Utility trucks typically have a channel chassis or frame that spans the length of the truck. A forward cab portion and a rearward utility body are attached to and rest upon the truck frame. Traditionally, the rearward utility body of the truck is attached to the frame by welds between the utility body and the frame or by other conventional rigid attachment means. During movement of the truck, the rigidly attached utility body will move with the truck frame thus experiencing abnormal stresses. For instance, as a utility truck travels over curbs or other uneven surfaces, the utility body will tend to twist with the truck frame, which stresses the body. This twisting action places heightened stresses upon the door openings, latches, and hinges of the utility body. Over time, these stresses degrade the integrity of the body, leading to failure.
Several flexible mounts have been developed that can secure a utility body to a truck frame while resisting the undue stress created by the truck's movement. U.S. Pat. No. 4,862,983 by Kreft, for example, discloses a truck body mount that employs two compression springs. Depending upon the twisting action of the truck frame, the springs will either expand or compress to minimize this motion and absorb the energy that would otherwise be transferred to the fixed portions of the mount.
One disadvantage of conventional flexible mounts is that they do not critically dampen the energy transferred between the utility body and the truck frame during movement of the truck. As the utility body twists about the truck frame during movement of the truck, conventional flexible mounts tend to oscillate vertically, creating a harmonic bounce. As the utility body plunges toward the truck frame, one of the compression springs of a conventional flexible mount will compress while the other compression spring will expand. This energy is not dampened by the springs, but rather transferred back and forth between the two springs, causing the utility body to oscillate vertically about the truck frame.
Another disadvantage of conventional flexible mounts is that they do not adequately limit the flexible motion between the utility body and the truck frame during movement of the truck. Because conventional flexible mounts are held together primarily by a pair of unguided springs, the mount is permitted to travel in any direction that the springs provide. The dual spring system of conventional flexible mounts allows for lateral motion between the utility body and the truck frame as they move up and down, from side to side, or front to back. This virtually unrestrained and unfettered motion contributes to the dampening problem described above.
It is therefore a principal object of this invention to provide a flexible utility body mount that can critically dampen the energy transferred between the utility body and the truck frame during movement of the truck.
A further object of this invention is to provide a flexible utility body mount that can adequately limit the lateral motion between the utility body and the truck frame during movement of the truck.
Yet another object of this invention is to provide a flexible utility body mount that is simple to use and repair and provides these benefits economically.
These and other objects will be apparent to those skilled in the art.